Hypohidrotic (anhidrotic) ectodermal dysplasia (HED), the most common of the approximately 150 described ectodermal dysplasias, is a disorder characterized by abnormal development of hair, teeth, sweat glands and salivary glands. Mutations in the: EDA and EDAR (EDA receptor) genes are responsible for X-linked and autosomal HED, respectively; abnormal phenotypes similar to HED are seen in Tabby (Eda-Ta) and downless (Edar-dl) mutant mice. Given the observation of abnormal submandibular salivary glands (SMG) in patients with HED and, similarly, in Tabby (Ta) and downless mice, our immunolocalization:of Eda and Edar proteins on embryonic SMG epithelia, and that our finding enhanced or interrupted Eda/Edar signaling in vitro modulates SMG branching morphogenesis, we postulate that Ecla/Edar signal transduction is essential for SMG development. To delineate the role of Eda/Edar signaling during embryonic SMG development, WE PROPOSE to: (a) Determine the progressive, stage-dependent phenotypic outcome of abrogated Eda/Edar signaling in embryonic Ta mutant SMGs and compare it to that seen in wildtype (WT) and gene-restored Tabby-EDA-A1 transgenic mouse SMGs. SMG phenotypes will be defined by microanatomy, cell proliferation and apoptosis indices, level of NFkappaB activation, and mucin protein expression. (b) Delineate the functional genomics of abrogated Eda/Edar/NFkappaB signaling in embryonic Ta SMGs, as compared to WT and Tabby-EDA-A1 transgenic mouse SMGs, using transcriptomic and proteomic methodologies. (c) Identify the functional pathways directly or collaterally downstream of the Eda/Edar/NFkappaB signal by comparing changes in activated protein expression in embryonic Ta, WT, and Tabby-EDA-A1 SMGs. Finally, we will delineate the in vivo spatiotemporal distribution of activated proteins: modulated with interrupted Eda/Edar/NFkappaB signaling. The data generated by our proposed studies will provide the framework for future studies of SMG loss of function and will provide a rational basis for designing drugs that may be used to restore acinar form and function in damaged and aging SMGs.